Process of recovering metals from their ores



H. v. WELCH PROCESS OF RECOVERING METALS FROM THEIR ORES Filed July 19. 1921 QUXB {Wiku sum A T TORNEY 45 cont-ent of the fume,

Patented Feb. 19, 1924.

UNITED STATESl PATENT OFFICE.'

FORNIA.

PROCESS OFRECOVERING METALS FROM THEIR CRES.

Application led July 19, 1921. Serial No. 485,920. l

To all whom it may oovwem: I

Be it known that I, HARRY V. WELCH, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented-a new and l Metals from useful Process of Recovering I Their Ores, of which the following is a specifcation.

y This invention relates tO the recovery of copper and other metals from their ores by what is* known as the volatilization process in which the metallic values of the `ore are converted b heat and suitable reagents to the form o fume, which ais condensed and collected so as to provide the metallic values in concentrated form.,y

As generally carried Out for the recovery of copper the volatilization process involves the conversion of the copper to the form of chlorid, the copper chlorid being volatilized and the fume containingvsuch chlorid being collected by electrical precipitation, or Otherwise. In order to recover 4the copper in metallic form from the resultin fume product it is desirable tO' smelt the ume, or subject it to heating Operationv inl a suitable furnace. long with a reducing agent. By reason of the volatile nature of the copper A chlorid the smelting of the fume containing such chlorid is a matter of some difficulty, as the metallic values inthe fume tend to pass oil' or re-volatilize when subjected to the necessary temperature required for smelting. The main object of the present invention 35. is vto provide, a process whereby the copper in the fume is convertedI into a relatively non-volatile compound, ed without undue loss ofl copper by volatilization. f e 40 A further object of the invention is to carry out the process in such manner that the product which is eventually smelted is substantially free from chlorine, including not only the chlorine carried by the copper but' also any other chlorine which may be presentin the'fume, for example, residual chloridizing agent used in the volatilizating operation land carried 'over with the fume. The presence 4of such excess chlorine is also 'objectionable in the smelting Operation. for the reason that it tends to increase the volatilization of the copper content in the fume in the smelting operation and, bysubstantially removing which may be smeltf p a feeding means' 5,

feeding themixture of .collecting chamber 6, w

' chlorine from the fume, loss by volatilization in smelting the fume is substantially or largely eliminated.

Another ob] ect of the invention is to carry out the process in such manner that the product which is smelting is more concentrated as regards metallic values than the fume resulting from the primary volatilization Operation. A further object of the invention is to so carry out the process that the chlorine removed from the fume is brought into a con# dition for reuse in cyclic operation by the volatilization process.

The accompanying drawing is a flow sheet of the process.

' I will describe myinvention as applied to theprecovery of en per from ores thereof, for exam le, Oxidize ores, or sulfid ores, which have en roasted suliiciently for the opera-v tion of the process.

The suitably crushed or divided ore is heated in a furnace or kiln, indicated at 1, the same being, for example, a rotary kiln lrovided with a hood or burner 2 for pro- ]ecting a flame thereinto to heat the ore passing through the kiln to a sufficiently high temperature to cause volatilization of the copper content, able chloridizing agent being added along with the ore to enable such volatilization to be eiected. The crushed or divided ore may be drawn from the bin, supply means, indicated at izing agent, such cium chlorid, may be drawn from the sup- 'ly means 4, and pass along with the Ore to which is preferably na 3, and a chloridslurry feed device orey and chloridizing agent, along with water, in the form of a slurry tojthe kiln or furnace 1. Y

The hot gases produced in `the kiln or furnace 1 pass to a spra chamber Ordust ich ma be provided with spray means? for distributing water Orsolution thereinto so as' tO wash out the dust or heavier particles and at the same timecool the gases. The resulting sludge collected in the sprayI chamber an containing such heavier or coarser particles pass tO a thickener 8 of .any suitable type, the thickened sludge passing therefrom back to the slurry feed device 5. Thls thickened AssIGNon To INTERNATIONAL PEELl A CORPORATION or CALI- or other suitable as sodium'chlorid, Or calor a portieri therof, a suitsludge consists largely of gangue material blown from thekiln or furnace 1 inthe form ofdust but also contains some metallic values and is, therefore, preferably returned to the feed, as indicated. By reason of the cooling of the gases and vapors passing from the furnace or kiln through the spray chamber the metallic vapor, which, in the case of the treatment of copper ore with sodium chlorid, or calcium chlorid, consists largely of copper chlorid, will be collected in the form of fume in the fume collector 10 through which the gases pass after leaving the -spray chamber. This fume collector may be an electrical precipitator of the t pe shown in the patent to H. A Burnso. 1,250,088-December 11th, 19l7-or in the patent to H. V. lVelch-No 1,338,271- April'27th, 1920-in which the fume is collected in or on a stream of liquid. Other types of electrical precipitators may, however, be used for the purpose and the fume may be collected in dry orvsemi-dry condit1on and treated afterward with solution in the manner hereinafter described. A part of the overflow from the thickener or decantation device 8 may pass to the fume collector 10 incase the mode of. operation of same requires the application of a liquid, for example, inthe case of a wet electrical precipitator, as above referred to, or in the case a spray tower or absorption towerfis used. Another part of the overflow from the thickener or decantation device 8 may pass -to the spray chamber 7 as a part of the liquid sprayed thereinto. The residual gases or lbarren gases may be drawn from the fume collector 10 by means of a blower 12 and and may pass oi through a stack 13.

The fumev collected in the apparatus 10 and containing metallic values, such as chlorides of copper, lead, zinc, silver, or other metals to be recovered, .passes to an agitator, indicated at 14, wherein it is treated with a precipitating agent in the presence of water, such water being either supplied with the fume incase the values are being collected in a wet way, or being added to the fume after collection. In the case of fume containing chlorid of copper resulting from application of the volatilization process to copper-bearing ores, I prefer to use powdered limestone as the precipitating agent, the finely divided limestone being agitated in the apparatus 14 with the copper chloridbearing fume and water, resulting in the production of basic copper carbonate and calcium chlorid. The sludge from the agitator 14 is passed to a thickener 15 wherein the solution containing calcium chlorid is separated from the sludge containing the precipitated copper carbonate, together with gangue, and said solution passing o" from Ithe overl-low of the thickener to a later stage of the process, as hereinafter described and messes the sludge containing the precipitated basic copper carbonate passing preferably to a series of counter current decantation tanks 16 wherein it is washed with fresh water, the washings being returned to thecycle of operations, for example, to the spray chamber 7 and the solids being filtered .o-l' at 17.

rlhe solids produced in the above described manne-r and containing the metallic values of the volatilized fume are passed to a reduction furnace, indicated at 18, being preferably first briquetted in a suitable apparatus 19', together with coke furnished from a source of supply 20. The operation of the reduction furnace 18 in usual manner reduces the basic carbonate of copper to bullion. The gases passing off from the reduction furnace may pass, as indicated, to the inlet of spray chamber 6 and the slag from the said furnacemay be granulated -in a suitable apparatus 22 and added to the feed of the kiln 1. This slag is preferably granulated by subjecting it while still hot to contact with the overflow of the thickener 15 containing the calcium chlorid produced by reaction of the copper chlorid Wlth the limestone in the agitator 14. Consequently the granulated slag supplied to the feed of the kiln 1 contains a large proportion. of the chlorine originally supplied to the material passing to the kiln and, in fact, by the above described operation the major portion of the chlorine may be continually returned to the kiln in the form of calcium chlorid so that only suiiicient sodium chlorid or calcium chlorid need be added to the slurry to make up for waste.

The invention may also be applied to the recovery of metals other than copper, for example, lead and zinc. ln case lead is present and there is no considerable amount of sulfur in the kiln gases, then sulfuric acid may be added to the 4mixture of collected lead chlorid fume and Water to precipitate lead sulfate and thenv alkali, or alkali earth carbonate, oxid, or hydroxid added to neutralize the hydrochloric acid present and convert the `chlorine to a form suitable for return to. the kiln, namely, as alkali chlorid, or alkali-earth chlorid. Lead sulfate may then be separated from the gangue and other metal values, if `any are present, in the usual manner; or gypsum, or ma nesium sulfate maybe a 'tated with the mixture of collected lead c lorid fume and water to sulfate and recover the chlorine in the form of calcium chlorid, or magnesium chlorid, which may be returned to the kiln; or sufficient sulfur may be fed 'to the kiln to convert the volatilized lead to the form of lead sulfate, thelcollecting o eration being preferably carried out in tli presencel of water and the resulting sludge being treated with suitableV absorbing agents to recover produce a precipitate of lead the chlorine in the form of alkali or alkaline earth chlorid.

In case zinc is present in the ore, it may be collected in the form of zinc chlorid, which is brought into solution in any suitable manner and precipitated, for example, by means of an alkali or alkahne earth oxid, or hydroxid, such operation producing at the same time alkali or alkaline earth chlorid for cyclic use in the process.

In the case of an ore containing copper, lead and zinc, ,or any two of these metals, separation of same may be effected by lfirst treating the collected fume in the presence of water with an' alkali or alkaline earth sulfate (gypsum) to precipitate the lead as sulfate, the solution .being then separated and treated with alkaline earth carbonate (limestone) to precipitate coper as the basic carbonate, and the solution being again separated from the solids and treated with an alkali or alkaline earth hydroxid (calcium hydrate) to precipitate the zinc as hydrate. The chlorine associated with each of the metallic constituents is in each of the above cases converted to the form of an alkali or alkaline earth chlorid, which is returned to the volatilization stage of the operation for use -on a further quantity of ore, so that the chlorine, or a large proportion of same used in the volatilization operation, is continually recovered and reused and ony suflicient fresh chlorine, or chlorid (sodium chlorid, for example), need be added to make up for unavoidable losses in the operation.

In each of the above described precipitating operations it may be necessary or desirable to apply heat to the solutionduring -the agitating and precipitating operations in order to accelerate the precipitating oper'- ation and it will be understood that where several metals are present decantatio'n or filtration, or both decantation and4 filtration, may be necessary after each precipitating operation to separate the precipitate from tthe solution before the solution is subjected to the next precipitating operation, so as to obtain the yprecipitates ot the metals, for example, lead, copper and zinc, in separate condition, the 4process being, therefore, ef-` ective for separation as well as recovery of the several metals from their ores.

In case gold, or silver, or both, are present inthe ore, they will be preclpitated with the or any one or more of other metallic values abovev referred to, the gold and a part of the silver being precipitated along with the lead in the first precipitation, and the remainder of the silver being precipitated along with the copper.

The metallic values precipitated as above described including lead, copper and zinc, these metals, are in the form of anv oxygen-bearing compound of relatively low volatility and may, be fur ther treated by, smelting to recover the'metal volatilization stage of the process,

in the form of bullion Without objectionable loss from 'volatilization of the metal-bearing fumes. c

What I claim is: l

' 1. The process of recovering metals from their ores which'consists in subjecting the' ores in the presence of an alkali or an alkaline earth chlorid to suliicient heat to volatilize metallic values of the ores in the form of chlorid,collecting the resulting fumes of metallic chlorid, and treating the collected fumes in the presence of water with an alkali or alkaline earth compound capable of reacting with the metallic chlorid in the fume to precipitate the metallic values in a form less volatile than the said chlorid and to produce an alkali or alkaline earth c1110-, rid for cyclic use in the process.

2. The process of recovering ore in the presence of a chloridizing agent, to cause such metallic values to be volatilized in the form ofrchlorid, subjecting the gases produced in said operation to the action of liquid spray to separate dust therefrom, returning the solid material so collected tothe collecting the fume remaining in the gases after .removal of such dust, treating said fume in the presence of water lwith a reagent capable of precipitating tlie said metallic values in a form less volatile than the s aid chlorid, and of forming a soluble compound containing the chlorid of said metallic chlorid, separatng said soluble compound from the precipitate containing the metallic values, -and' returning said soluble chlorid containing compound to the volatilization operation.

3. The process of recovering metallic values frompores, which consists in heating the ore in the presence of a chloridizing agent toy volatilize metallicvalues in the form of chlorid, collecting the resulting fume containing 'such chlorid,1treating the fume in the presence of water .with a reagent adapted to precipitating the dized, relatively non-volatile fume, producing a solublechlorid capable of acting as a chloridizing agent in cyclic operation of the process, separating such precipitate fro'm the soluble chlorid, subjecting the metallic values from ores, which consists in heating the v metallic values in oxxand to precipitate to reducing operation by the acv ize lead and the' lead as sulfate and kto prducesin solu-1 tion a chlorid ofthe alkali or alkaline earth' metal, separatingthe resulting precipitate from the solution, treating the solution with alkali or alkaline earth carbonate toprecipitate the copper as basic carbonate and to produce in solution an alkali or alkaline earth" metal chlorid, separating the result- 1ngprecipitate from the solution and utilizthe alkali or alkaline earth metal chlo inrid a chloridizing the process.

.5. The process of recovering and separating metallic values -from ores of lead and obtained in the aforesaid operations` as agent 1n cyclic operatlon of zinc, which consistsin heating the ore in the a chlorldizing agent to volatilpresence of zinc values in the form of chlorid, collecting the resulting fume containing such chlorid, treating the fume in the' presence offwater with a sulfate of an alkali or v alkaline 'earth metal to precipitate the lead cyclic operation ofthe process.A

copper, lead and zinc,

with' an alkaline earth nietal carbonate to .6. The process of'recovering and separating metallic values from ores containing lng the ore in the presence of a chloridizin agent to volatilize chlorids of copper, lea

"and zinc, collecting suchchlorids and treatmgsame in the presence of water with alkali sulfate to precipitate 'lead-#inthe form of sulfate and to produce in solution an alkali' or alkaline earth metal'chlorid', separating the resulting solutionfrom the precipitate and treating it precipitate copper as basic carbonate and to produce in solution a further quantity of an alkali or alkaline `earth metal chlorid, separating the resulting solution from the prechlorid, sepawhich consists in heat- A neeaeee cipitate andztreating same with alkali or alkaline earth metal hydrate to precipitate zinc as hydrate and to producein solution a further quantity of alkali or alkaline earth metal chlorid and utilizing the alkali or alkaline earth metal clilorid produced in each of the aforesaid precipitating operations as a cllloridizing agent 1n cyclic operation of the'process.

't'. The' rocess of recovering and separating metal ic` values from ores of copper and zinc, which consists in heating the ore in presence of a '-ichloridizing agent to volatllize copper and zinc values in the form of chloride, collecting the resulting fume containing such chloride, treating the fume in the presence of Water with an alkaline earth metal carbonate to precipitate copper as basic carbonate and to produce in solution an alkalior alkaline earth metal chlorid, separating the resulting precipitate from the solution and treating the solution' with an 'alkali or alkaline earth metal hy' drate to precipitate zinc as hydrate and to produce in solution-a further quantity of alkali or alkaline earth metal chlorid, separating the solution from the precipitate and using the alkali or alkaline earth inetal chlorid obtained in the aforesaid operations as a chloridizing agent in cyclic operation of the process.

8. The process of recovering copper values from ores thereof, "vhich consists in heating the ore in the presence of a chlor idizing agent to volatilize copper values in 4 the form of chlorid, 'collecting the resulting fume containing copper chlorid, treating the fume in the presence of water with an alkali or alkaline earth metal carbonate to precipitate copper values and to produce a solutlon containing alkali or alkaline earth metal chlorid, separating the resulting solution from'the precipitate and utilizingsucli alkali or alkaline earth metal chlorid as a chloridizing agent in cyclic operation of the process.

In testimony whereof l have hereunto subscribed 1921.

Har V. Weten'.

esV

:ny name this 12th day of July, 

